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Rizvi, V. A.

Publications and source records attributed to Rizvi, V. A..

2 recordsLinked to original sources

Life cycle process dependencies of positive-sense RNA viruses suggest strategies for inhibiting productive cellular infection

Life cycle processes of positive-strand (+)RNA viruses are broadly conserved across families, yet they employ different life cycle strategies to grow in the cell. Using a generalized dynamical model for intracellular (+)ssRNA virus growth, we decipher these life cycle determinants and their dependencies for several viruses and parse the effect of viral mutations and host cell permissivity. We show that Poliovirus employs rapid replication and virus assembly whereas Japanese Encephalitis virus leverages its higher rate of translation and efficient cellular reorganization compared to Hepatitis C virus. Stochastic simulations of the model demonstrate infection extinction if all seeding viral RNA degrade before establishing robust replication. The probability of productive cellular infection is affected by virus-host processes, defined by early life cycle events and viral seeding. Synergy among these parameters in limiting infection suggests new avenues for inhibiting viral infections by targeting early life cycle bottlenecks.

microbiology

Translation regulation of Japanese encephalitis virus revealed by ribosome profiling

Japanese encephalitis virus (JEV), a neurotropic flavivirus, is the leading cause of viral encephalitis in endemic regions of Asia. Although the mechanisms modulating JEV virulence and neuroinvasiveness are poorly understood, several acquired mutations in the live attenuated vaccine strain (SA14-14-2) point towards translation regulation as a key strategy. Using ribosome profiling, we identify multiple mechanisms including frameshifting, tRNA dysregulation and alternate translation initiation sites that regulate viral protein synthesis. A significant fraction (~ 40%) of ribosomes undergo frameshifting on NS1 coding sequence leading to early termination, translation of NS1' protein and modulation of viral protein stoichiometry. Separately, a tRNA subset (glutamate, serine, leucine and histidine) was found to be associated in high levels with the ribosomes upon JEV infection. We also report a previously uncharacterised translational initiation event from an upstream UUG initiation codon in JEV 5' UTR. A silent mutation at this start site in the vaccine strain has been shown to abrogate neuroinvasiveness suggesting the potential role of translation from this region. Together, our study sheds light on distinct mechanisms that modulate JEV translation with likely consequences for viral pathogenesis.

microbiology